1. Field of the Invention
This invention concerns a method for the industrial production of hose of vulcanizable elastomeric material such as natural or synthetic rubber, in particular hose of considerable length, in general at least in the region of 100 meters or more.
2. The Prior Art
It is known in this art to produce such hose by a sequence of steps including (i) the prefabrication of natural or synthetic rubber tapes, some of which are preferably rubberized cloth or otherwise formed by joining a layer of rubber (meaning by this expression, any suitable vulcanizable elastomeric material) to a tape or cloth cushion, (ii) the winding of these tapes after previously reducing a primary tape of considerable width down to single tapes which are individually of widths most convenient for the manufacture of the hose, around metallic cores of a length corresponding to the length of hose desired, (iii) thermal treatment of the partly finished product in an autoclave to carry out its vulcanization, and (iv) the extracting of the core from the length of vulcanized hose.
Obviously, the complete method necessarily includes some complementary stages such as the preliminary application of anti-adhesive, preferably zinc stearate, to the surface of said tapes to prevent mutual adhesion between the windings of the coils into which the tapes are formed.
These principal and complementary stages require observance of particular conditions, in general known to experts in the art and the overcoming of considerable and serious difficulties in connection with the lengths of hose intended to be produced.
On the other hand, the desirability of producing and marketing hose in lengths as a long as possible is well known. It is sufficient to consider, in this regard, the evident advantages consequent upon the reduction in the number of joints to be carried out during the installations of long piping systems, for example, aqueducts, oil pipelines, gas pipelines and the like, and the security of sealing and resistance resulting from the presence of only a small number of joints, with a considerable distance between them, in the installed hose.
The complete procedure can be divided, in general, into two groups of stages, one group including the productive operations leading to the pre-formation of the tapes, wound in coils suitable for helical winding of the tapes around the core, these stages being in their turn essentially independent of the length of hose to be produced, and one group of stages which lead specifically to the production of hoses and their separation from the cores around which they have been assembled and vulcanised. However, the technical solutions needed to resolve the specific problems for the different stages must be compatible, and there exist mutual connections as a result of which the production of the initial partly-finished product (typically, the rubber tapes), must not militate against but rather must favour the assembly of pieces of great length. For example, however much, during the winding, successive lengths of tape can be interconnected, it is at least of great advantage to be able to have at one's disposal coils of tape which unwind perfectly and which include, in their turn, considerable lengths of tape, in such a way as to not jeopardize the regularity of the winding or the assembly of very long pieces of hose.